Synchronous-type circuit interrupter with holding magnet for releasing latching means



NOV- 2, 1965 F. KEssx-:LRING ETAL 3,215,797

SYNCHRONOUS-TYPE CIRCUIT INTERRUPTER WITH HOLDING' MAGNET FOR RELEASING' LATCHING MEANS ATTORNEY Nov. 2, 1965 F. Kr-:ssELRlNG ETAL 3,215,797 -TYPE CIRCUIT INTERRUPTER WITH HOLDING SYNCHRONOUS MAGNET FOR RELEASING LATCHING MEANS 2 Sheets-Sheet 2 Filed Dec. 20, 1962 YTIME Fig.2.

Fig.4.

United States Patent O 3,215,797 SYNCHRONOUS-TYPE CIRCUIT INTERRUPTER WITH HOLDING MAGNET FOR RELEASING LATCHING MEANS Fritz Kesselring, Kusnacht, Zurich, Ernst Gisiger, Zurich, and Lutz Seguin, Bergdietikon, Switzerland, assignors to Siemens-Schuckertwerke Aktiengesellschaft, Erlangen, Germany, a corporation of Germany Filed Dec. 20, 1962, Ser. No. 246,231 Claims priority, application Germany, Dec. 28, 1961, S 77,341 15 Claims. (Cl. 200-91) This invention relates generally to synchronous-type circuit interrupters, and, more particularly, to improved and highly effective extinguishing structures, and to operating and control arrangements for such synchronoustype circuit interrupters. The present invention has particular application to gas-blast type circuit interrupters in which a blast of gas is utilized to effect arc extinction, but is not limited solely to such type of structures.

A general object of the present invention is to provide an improved and highly eilicient synchronous-type circuit interrupter in which the separable contacts are opened on the descending portion of the alternating current wave, say, for example, approximately 2 milliseconds prior to a current zero with relation to a 50-cycle-persecond frequency.

Another object of the present invention is the provision of improved reclosing arrangements for synchronous-type circuit interrupters in which the separable contacts may be reclosed upon the occurrence of an unsuccessful synchronous interruption, or upon the occurrence of a transient fault current during a normal load-breaking operation.

Another object of the present invention is the provision of an improved simplified-type and highly efficient synchronous circuit interrupter in which the consumption of the arc-extinguishing fluid is kept at a minimum.

Still va further object of the present invention is the provision of improved and highly effective reclosing means for a circuit interrupter, particularly one of the synchronous type.

In United States patent application eld March 22, 1961, Serial No. 97,656, entitled Synchronous Circuit Interrupting Devices by Fritz Kesselring and Lutz Seguin, and assigned to the assignee of the instant application, there. was proposed the use of a synchronous operator in connection with circuit interrupters to actuate contact movement and to control component parts of the circut-interrupting structure. Also, in United States patent applications filed August 29, 1961, Serial No.

134,655, and likewise assigned to the assignee of the instant application, there are disclosedimprovements relating to synchronous-type circuit-interrupting devices utilizing compressed gas as the arc-extinguishing fluid, and controlling contact movement as a function of instantaneous value of the interrupting current. Also, in United States patent application tiled March 27, 1961, Serial No. 98,522 by Fritz Kesselring, and assigned to the assignee of the instant application, there is disclosed and claimed an improved blast-valve damper means functioning as a synchronous device operable shortly before current ze-ro to inject an arc-extinguishing blast of gas into the arc shortly before current zero to effect thereby a minimum of consumption of blast energy. Accordingly, it is a further object of the present invention to improve upon the synchronous-type devices, as set forth in the aforesaid patent applications, rendering them less complex in nature, and utilizing, in addition, improved reclosing arrangements for rapidly effecting reclosure upon unsuccessful interruption of the controlled circuit.

Patented Nov. 2, 1965 ice Still a further object of the present invention is the provision of an improved synchronous-type operator for a gas-blast circuit interrupter.

Another object of the present invention is the provision of an improved circulating-type gas-blast circuit interrupter suitable for use with a relatively expensive arcextinguishing fluid, such as sulfur-hexafluoride (SFS) gas, which may be recompressed and utilized over and over again for subsequent interruptions.

Still a further object of the present invention is the provision of an improved magnet system for generating a control current which is phase-shifted with respect to the main curre'nt being interrupted.

Still another object of the present invention is the provision of an improved synchronous-type circuit interrupter in which highly efficient reclosing means is provided, and which utilizes a control current which is phaseshifted with respect to the main current being interrupted.

Still a further object of the present invention is the provisin of an improved synchronous-type circuit inter- Irupter in which a tripping impulse, either effected manually or automatically, is delayed by synchronously-functioning means to permit separation of the separable contacts only during the descending portion of the current wave, say at a time roughly of the order of 2 milliseconds before a current zero on a 50-cycle-per-second basis as well known by those skilled in the art, by interrupting the controlled circuit close to a current zero, the consumption of blast energy and the generation of arc energy is reduced to a minimum.

According to one aspect of the present invention, a synchronous-type circuit interrupter is provided with means for eifecting instantaneous reclosing following an unsuccessful synchronous interruption. A movable contact, which is biased toward the open position by an opening accelerating spring, is held in a latched position by a holding magnet, which is energized by a control current, which is phase-shifted With respect to the main current, and which holds the breaker closed until the control current falls below a predetermined value. Moreover, there is additionally provided an electrodynamic system, which, after an unsuccessful synchronous interruption, releases an interlock, by which is initiated the operation of a reclosing energy accumulator using, for example, compressedy air, or other compressed gas.

It has already been proposed to build synchronous-type circuit interrupters, such as those set forth in the preceding patent applications, in which the contact separation takes place shortly before the main current passes through its current zero, and in which, following an unsuccessful interruption of the current which is to be interrupted, there occurs an instantaneous reclosing operation. In such an eventuality, there occurs at least another opening shortly before the next passage of the main current through its zero value. By the design of such synchronous-type circuit interrupters, it has been made possible to utilize effectively circuit interrupters for multiphase networks in which, under some conditions, there may be present very complex problems of interruption due to the various shifts of the individual phase currents. There has been proposed, among other control devices, those utilizing an dz' z/dt release trip, rotating moving coils, or sliding moving coil systems, with which successful switching experiments have already been made possible up to very considerable capacities.

The present invention is particularly concerned with an operating device for synchronous-type circuit interrupters having instantaneous reclosing in the case of unsuccessful synchronized interruption, and controlling the passage of the current through its zero value. The circuit-interrupting device of the present invention is particularly distinguished by an interlocking system, which holds the breaker in its closed position against an opening force, on one hand, by a mechanicaly lacking device and, on the other hand, by a holding magnet, which is energized by a control current derived from the main current to be interrupted, and which is phase-shifted with respect to it. In such manner, the holding magnet is operable, in case of an arbitrary release of the mechanical locking device, to hold the interlock in the current circuit of the synchronous control until such time as the control current falls below a predetermined minimum value. The device of the present invention is additionally distinguished by the utilization of an electromagnetic system, the magnetic circuit of which is energized from the main circuit, and within which a movable conductor is positioned, carryingv the control currrent, so that upon the occurrence of Aan unsuccessfulV synchronized interruption, or by the occurrence of a transient fault condition, the electrodynamic system produces forces in a fraction of a millisecond, for example, for bringing about a reclosing operation.

Further objects and advantages will readily become apparent upon reading the following specication, taken in conjunction with the drawings, in which:

FIGURE 1 illustrates a vertical sectional view taken through a synchronous-type circuit interrupter embodying the principles of the present invention, with the contact shown in the closed-circuit position;

FIG. 2 is a fragmentary enlarged view of the holding latching arrangement utilized in connection with the synchronous-type circuit interrupter of FIG. l, the parts being illustrated in the open-circuit position just prior to the occurence of a reclosing operation;

FIG. 3 is a fragmentary sectional view taken substantially along the line III-III of FIG. 2;

' FIG. 4 is a diagrammatic view illustrating the ux conditions and the magnitude of the control current in the magnetic system of FIG. 3;

` FIG. 5 diagrammatically illustrates the relationships between the control currents in a magnet system having little saturation, and in which various magnitude main currents are encountered;

FIGS. 6-9 diagrammatically illustrate various fault current conditions and the accompanying control currents, which are generated with such varying fault current conditions; and

FIG. illustrates .a modified type holding magnet arrangement.

`Referring to the drawings, and more particularly to FIG. l thereof, the reference numeral 1 generally designates a synchronous-type circuit interrupter. Generally, the synchronous-type circuit interrupter 1 includes an arcextinguishing section 2, an operating system 3, and a control system 4.

The arc-extinguishing section, or system 2 generally includes a relatively stationary orifice contact 5, through which a gas blast may ow, and a cooperable movable contact 6. As shown, the movable contact 6 is xedly secured to the upper end of an operating rod 7 having secured to the lower end thereof an abutment 8, which, in turn, serves as the lower seat for an accelerating compression spring 9. As a result, the accelerating compression spring 9 biases the movable contact 6 downwardly toward an open-circuit position away from the stationary contact 5. As well known by those skilled in the art, the separation of the main contacts 5, 6 will effect the drawing of an arc through the nozzle 10 associated with an orifice member 11 disposed in the upper end of a generally cylindrical-type casing 12 having a line terminal connection 13 at its upper extremity. The line terminal connection 13 is preferably made an integral part of an arc'ing electrode 14, to which the upper terminal of the established arc may terminate during the opening operation.

Controlling the upward flow of an arc-extinguishing blast of gas from a high-pressure region 15 to a generally low-pressure region 16 is a laterally-movable blast valve 17, the particular .construction of which is set forth and claimed in United States patent application filed January 16, 1963, Serial No. 251,885 by Fritz Kesselring and Hansruedi Aumayer, entitled Valve Structures, and assigned to the assignee of the instant application.

As shown in FIG. 1, the interrupting casing 12 is supported by a support insulator 18, through which extends a low-pressure outlet 19, a high-pressure inlet 20, and an insulating blast-valve operating rod 21. The blastvalve operating rod 21 is pivotally connected, as at 21a, to a bell-crank lever 22 pivotally mounted upon a stationary pivot 23. To one of the arms 24 of the operating bell-crank lever 22 is pivotally connected, as at 25, an operating rod 26 having an abutment 27 secured to the lower end thereof. The abutment 27 serves as the-upper seat for a compression spring 28 enclosed within a generally cup-shaped member 29, and serving, in conjunction with the abutment 27, as a lost-motion device, generally designated by the reference numeral 30.

The operating cylinder 29 is secured to the upper end of an operating rod 31 xedly secured to the upper end of an armature 32, to the lower end of which is likewise fixedly secured an operating rod 33. vThe operating rod 33 is pivotally connected at its lower extremity to an operating bell-crank 34, as at the pivotal connection 35.

The operating bell-crank 34 is pivotally mounted upon a stationary pivot 36, and has one varm 37 pivotally connected, as by a pin-and-slot connection 38, to a rod end 39. The rodl end 39 is xedly secured to the lefthand end of a trip rod 40, as viewed in FIG. l.

As shown in FIG. 1, the insulating trip rod- 40 passes laterally through the interrupter casing 12 into a boss portion 12a thereof, and has a washer abutment 4'1 iixedly secured thereto to constitute the left-hand seat of a compression spring 42. As shown, the compression spring 42 encircles the trip rod 40, `and has its righthancl end bearing upon the lower extremity 43 of a latch 44 having an armature portion 45 secured thereto. rlhe armature portion 45 is, at times, attracted to a holding magnet 46, which encircles a control circuit 47, which includes a movable control armature bar 48.

With reference to FIG. 2 of the drawings, it will be noted that the movable control armature bar 48I is pivotally connected, as at 49, to an electrodynamic magnet system 50 which encircles a main conductor stud 51, which terminates in a lower line terminal portion 52. A second line conductor L2 may be aixed to the lower terminal 52 of the interrupter 1, and the current passage through the interrupter 1 preferably comprises line conductor 52., main conductor stud 51, bracket portion 53, valve seat plate 54, the walls 55 of an expansion chamber 56 associated with an operating cylinder 57', and through an upstanding cylindrical spring enclosure 58', encircling accelerating compression spring 9, and also constituting a main conductor portion of the interrupter.

'Io electrically carry the current between` the movable main contact 6 and the cylindrical spring housing 58, there is preferably provided a plurality of circumferentially-disposed contact lingers 59, encircled by a garter tension spring 60, and biased radially inwardly into good contacting engagement between an upper recess portion 61 of line conductor 58, and rollers 62 interposedbetween the upper ends 59a of contact ngers 59 and the sides of the movable main contact 6.

The operating system 3, in addition, includes an operating piston 63 iixedly secured, as by a pin connection 64, adjacent the lower end of operating rod 7. A compression spring 65 encircles the lower operating rod portion 7a and abuts a s-lidable ring 66, which, at times, makes abutting engagement with a blast valve 67 lixedly secured to, and operated by, an operating valve S lever 68. The valve lever 68 is pivotally mounted upon a stationary piv-ot 69. The pivot 69, in addition, serves as a pivot for the aforementioned latch lever 44.

A pin 70, passing latera-lly through the lower end 7a of the operating rod 7, picks up the operating valve 67 toward the end of the closing operation of the movable contact 6.

The casing 12 includes an upper insulating closure member 71, a lower closure member 72, and interiorlydisposed suitable-configured insulating spacing sleeves 73, 74 and 75. As shown, the spacing sleeves 74 and 75 have longitudinal bores 76 provided therethrough to form interconnecting conduits interconnecting the low-pressure region 16 with the region 77 interiorly of the expansion chamber 56.

In the particular embodiment of the invention shown, there is provided a recirculating gas system 78, whereby a relatively effective arc-extinguishing gas, such as sulfur hexafluoride (SP6) gas, is utilized as the arc-extinguishing gas.

A high-pressure chamber 79 is provided generally interiorly of a low-pressure chamber 80; and both of the chambers are, in turn, disposed interiorly of a grounded casing 81 preferably supported upon a support panel 82 by suitable brackets 83. Interconnecting the highpressure chamber 79 and the low-pressure chamber 80 is a suitable compressor 84, which may be responsive to certain pressure gauges and control equipment, not shown, to maintain the requisite high-pressure level of the gas within the high-pressure chamber 79. Additionally, it will be noted that the whole of the interrupting casing 12 below the blast valve 17 is at relatively high pressure, whereas the region 16 above the blast valve 17 and the region 77, interiorly of the expansion chamber 56, and above the valve 67, is at relatively low pressure.

In the closed-circuit position of the circuit interrupter 1, as illustrated in FIG. l, it will be apparent that the main current path through the interrupter includes line connection L1, line terminal 13, spider support 85 for Vsupporting arcing electrode 14, spider members 85a, orifice member 11, relatively stationary fingers 5, movable contact 6, rollers 62, bridging fingers 59, main conductor 58, operating cylinder 57, valve plate 54, bracket portion 53, lower main conductor 51, to line terminal 52 to line conductor L2.

As shown in FIG. l, in the closed-circuit position of the interrupter 1, the interrupter is held in the closed position by the latches 44, 68 and the trip bar 40. If the interrupter 1 is to be opened, then first the tripping coil 86 is energized, in an impulse like manner, as, for example, by the discharge of a suitable associated capacitor. As shown, a protective relay 86a, responsive to the fault current in the line L2, or a manual trip button 86b may be used to energize the tripping coil 86 from sources of 'energy 100, 101. This results in a downward movement CII of the armature 32, whereupon the bell-crank lever rotates about the shaft 23 in a counterclockwise direction. VThis causes the blast valve 17 to be opened, that is moved 'toward the left, as viewed in FIG. l, by the insulating vblast-valve operating rod 21. However, a liow of the `high-pressure gas from the region 15 into the outlet region 16 does not occur at this time, inasmuch as the movable contact 6 is still in contacting engage-ment with the relatively stationary nozzle-like -contact 5, and consequently, to a considerable extent, blocks the gas passage through the orifice opening 10.

Simultaneously with the rotative movement of the operating bell-crank 22, there also occurs rotation of the operating bell-crank 34. After traveling through the -[length of the pin-and-slot connection 38, the insulating operating trip bar 40 moves to the left, and causes release of the latch 44, whereby the opening sequence is initiated. vIt will be assumed that the main, and therefore also the control current, are so small in magnitude that the arma ture 45 of the holding magnet 46 is not held against the force of the compression spring 87. The accelerating spring 9 will consequently force the movable contact 6 downwardly and unplug the orifice 10, to permit the gas blast to extinguish the established arc.

However, during the occurrence of relatively large currents, for example, approximately twice the nominal, or load current, and particularly during the occurrence of short-circuit currents, the synchronized control 4 will at this time come into play in the following manner: When the impulse t-o trip is given, again the tripping coil 86 is energized at any arbitrary instant on the current wave, and the blast valve 17 is withdrawn laterally to open the nozzle exhaust 10. The tripping bar 40 is moved to the left, and the main current flowing through the interrupter 1 is changing as a function of time. The main current iow through the main conductor 58 causes a flux change in the magnetic system 88. At the same time, there appears between the points A and B on ohmic voltage drop. In order to produce an ohmic Voltage drop of sufficiently high value without reducing the crosssectional area of the conductor 58 too much, it may be of advantage to make the main conductor 58 and the operating cylinder 57 of a material having a resistivity higher than that of copper, for example, of brass or of bronze.

In the closed-circuit starting with point A, along the line 47 leading through the holding magnetic system 46, through the movable conductor 48 up to the point B and back through the operating cylinder 57 and the main conductor 58 to the point A, there is produced, partly due to the change of flux in the magnetic system 88 and partly due to the ohmic voltage drop mainly in the main conductor 58, a resultant volta-ge, which forces through the mentioned loop circuit the control current i2. This control current i2 energizes the holding magnet 46 and results in that despite the withdrawing of the trip bar 40, nevertheless the synchronized breaker 1 will not start the opening, or tripping movement immediately, but only when the control current i2 falls below a predetermined value, at which time the armature 45 releases under the effect of the compression spring 87. When this occurs, the latch 44 is released without any time delay, that is instantaneously.

It will be apparent that latching means 44 for latching the separable contacts 5, 6 in their closed position is released by an actuated condition of a first mechanical re lease operator 40 and a second release timing operator 46, energized by a phase-shifted current i2 with respect to the main circuit current i1. The control current i2 passes in the secondary circuit 47', which includes the rotatable control armature 48, a part of the electrodynamic system 50.

The reclosing valve 67, valve lever 68 and prop latch 48 constitute a reclosing operator 99, which functions during unsuccessful synchronous operations, to reclose the separated contact structure 5, 6 and wait for a time close to the next current zero for the latching means 44 to again function. Such opening and reclosing may continue until the circuit is interrupted, thereby conserving arc energy.

The essence of the synchronized control 4 then consists in that this minimum value of the control current i2 is reached, for example, approximately I2 milliseconds before the main circuit current passses through its zero value, which can be obtained through a suitable choice of the inductive and ohmic components of the seondary circuit 47, while taking into consideration the saturation phenomena in the magnetic system 88, as more fully described hereinafter in connection with FIGS. 6-9 of the drawings. As loug as interruption takes place, that is, as long as the arc remains extinguished at the time of the main circuit current passing through its zero value, the breaker 1 will remain in the open position, as indicated in FIG. 2 of the drawings.

It is true that the compression spring 65 encircling the operating rod exerts pressure upon the reclosing valve disc 7 67, but this is latched closed through the latch lever 68, and alsoby the pivotal movable control conductor 48, so that the reclosing valve 67 cannot open. Under the compressive force of the spring 89, the blast valve 17, as well asy the trip bar 40 move in a predetermined time of, for example, three half cycles, on the basis of 50 cycleper-second frequency, back into the position shown in FIG. l. This result can be achieved by properly selecting the several movable masses and the spring 89 with respect to each other.

If the circuit interrupter 1 is to be closed, then either the left-hand end of the trip bar 40 is mechanically moved in the direction indicated by the arrow 90, or else the closing coilv 91 is energized by a closing button 91a so that the armature 32' is drawn upwardly. As a result, the spring 28, within the lost-motion connection 30, is compressed so that the bell-crank lever 22 remains stationary. By movement of the tripping bar 40 to the right, as viewed in FIG. 1, the movable control conductor 48 is rotated from the illustrated position of FIGS. 1 and 2 clockwise, whereupon the operating latch lever 68 is released, and the closing valve 67 is opened under the effect of the compression spring 65 encircling the lower portion 7a of the operating rod 7.

When this occurs, the high-pressure gas within the region 15 flows upwardly into the operating cylinder 57 to act upon the lower surface of the operating piston 63. This will effect upward closing movement of the movable main contact 6 and effect reengagement of the main contact 5, 6. Toward the end of the closing operation, the pin 70 secured to, and movable with, the operating rod portion 7a will reengage the closing valve 67, and carry the operating valve 67 to its closed position, as shown in FIGS. l and 2, in which position it is again latched.

When the closing sequence has been completed, the tripping` rod 40 is pushed by the springs 92 and 42 back into the position shown in FIG. 1. In the final position, shownl in FIG. 1, the tripping rod 40 is acting, through the bell-crank lever 34, through the lost-motion connection 30, which, in this position, represents a rigid connection, and through the bell-crank lever 22 against the effect of the compression spring 89. The effect of the compression spring 89 'over-balances the effect of springs 92 and 42. If, for any reason, the arc-extinguishing action at current zero does not take place, or if during an interrupting operation of a smaller current magnitude there occurs a so-called transientfault, then the movable conductor 48 is rotated in a clockwise direction about its pivotal support 49 by a large force under the eifect of the considerable magnetic flux present within the air gap 93 (FIG. 3) of the electrodynamic magnet system 50. When this occurs, the reclosing valve 67 is released in the same manner as in the case of a manual closing operation. As a result, it is of considerable importance that in the air gap 93 (FIG. 3) there occurs at approximately double nominal current maximum induction B of at least 15,000 Igauss, and that at the same time the control current i2 has a very high value, as indicated inl FIG. 4 of the drawings. As well known by those skilled in the art, the electrodynamic force which results is in accordance with the formula:

where L is equal to the 4active length 'of the conductor '48. The large force F in Equation (1) results in the release of the reclosing valve 67 in a fraction of a millisecond. After being released, the valve 67 can move downwardly as a result of compression of gases below the piston 63, which compression is, under certain circumstances, supported also by the eifect of the spring 65. As a result instantaneous reclosing Will take place in opposition to the effect of accelerating compression spring 9 in a time of 1 to 2 milliseconds.

Immediately after a reclosing operation, the latch 94 effect of the compression spring 92, so that the circuit` interrupter 1 is ready for another synchronous opening operation just prior to the next passage of the main circuit current through its zero value.

It will be observed that in the closedcircuit position of the circuit interrupter 1, as illustrated in FIG. 1 of the drawings, instantaneous exhaust of the operating cylinder 57 occurs through the exhaust openings 96 when the operating piston 63 is in its contact-closed or upper position.

As shown, the exhaust openings 96 lead into the expansion space 56, which leads, in turn, by way of the conduits 76, to the low-pressure region 16 of the interrupter 1. It is very important for rapid exhausting of the region 97 below the operating piston 63 that the expansion space 56 be connected with the operating cylinder 57 directly, and through the shortest possible exhaust pipe connections, which preferably, may assume the form of the exhaust openings 96. As a result, the exhausting of the gas from the region 97 may occur in a time of approxi-- mately 1 millisecond.

The 'occurrence of a transient fault condition during a load opening operation will result in, the movable control conductor 48 rotating clockwise with considerable force in exactly the same manner, whereupon an instantaneous reclosing operation follows. Shortly before the next passage of the 4main circuit current through its zero value, a synchronized tripping interruption takes place in the previously described manner.

In the following discussion, the method of synchronized control over the entire current range from approximately twice nominal, or load current -up to the highest shortcircuit currents will be explained. As a result, it is possible to differentiate between a magnet system 88, the air gaps of which are so generously dimensioned, so that practically no saturation occurs, and an arrangement in which the saturation phenomena of the magnet system 88 is purposely exploited to the best advantage.

With reference to FIG. 5 of the drawings, it will be observed that there is rst diagrammatically illustrated a case of practically an unsaturated magnet system 88. i2 is the current component corresponding t-o the inductive voltage component. i2 is the current component corresponding to the ohmic Voltage drop, particularly -in Conductor 58, under an assumption that approximately double the nominal, or load current ows through the interrupter 1. The sum of these two current components yields the resultant control current i2 with a slope a at its zero point. The time current curve of control current corresponding to approximately ten-times nominal, or load current is illustrated by the dash line (i2). The corresponding notations are made in parentheses for facilitated distinction .and comparison. It Will be apparent from a study of FIG. 5 that the slope ,8 is equal to 5 times the slope a. Because of this steep slope of the control current (i2) the release of the armature 45 of the holding magnet 46 is rendered uncertain. This uncertainty can be avoided by arranging in the circuit 'of the control current a so-called phase reactor, which, of course, may mean an additional expense. Furthermore, the large dimensions of the magnet system 88 are disadvantageous, because of the considerable air gaps, a larger cross-section of iron is necessary in order to produce sufficiently large variations of the flux.

With reference to FIGS. 6-9 of the drawings, the behavior of the synchronized control 4 with a self-saturating magnet system 88 may now be investigated. It is assumed 9 that the main circuit current i1 begins with the illustrated half-wave and that the time constant Lz/RZ of the control current circuit 47, which is decisive for a progressive build-up of the control current i2, is small in comparison with the time interval of a half-wave.

FIG. 6 illustrates a condition corresponding to approximately twice the nominal, or load current. The notations for the currents correspond to those of FIG. 5. The slope of the control current i2 is small, its passage through its zero value being relatively far ahead of the passage through zero of the main circuit current i1, in the present case approximately 3 milliseconds. FIG. 7 corresponds to the conditions at approximately four-times nominal current, whereby already a slight saturation phenomena can be noticed in that the flux curve is somewhat flattened, which results in a slight deformation of the inductive component i2 of the control current. At the ten-times nominal current, corresponding to FIG. 8, already a strong saturation prevails. The :slope of the current i2' in the neighborhood of its passage through zero is even smaller than at the four times nominal current corresponding to the FIG. 7 condition, While the slope of the control current z2=z'2l-z`2 at its passage through zero, characterized by the time tv of the control advance, increased only slightly. From this it can be realized that through the application of stauration of the magnetic system 88, it may be achieved to control the maximum slope of the control current, so that the slope does not exceed the predetermined maximum value.

FIG. 9 illustrates the behavior of the synchronized control 4 at interrupting a sharply shortened half-wave. Because of the relatively high frequency of the sinusoidal current substituted for the small current half-Wave, the slope of the inductive component i2 is also considerable, while the ohmic component is independent of this substituted frequency. The passage through the zero value of the control current i2 follows very shortly behind the maximum of the primary current il, so that also in this case a still sufcient time tv of the control advance is available for synchronized release. So that the control current i2 adjusts itself fast as possible to its constant value, it is necessary that the magnet time L2/R2 amounts at the most to 2 milliseconds. L2 is the total self-inductance of the secondary circuit 47 including the inductance of the holding magnet 46 and of the electrodynamic system 50 and R2 is the respective resistance. It is realized that it is of advantage to design the interlock 44, 94 with such characteristics so that the dimension of the holding magnet 46, and thereby also of the magnet system 50, `may be relatively small. These small dimensions, in turn, result in a small self-inductance L2, which is also at saturation still further reduced.

The use of saturation in the magnetic system 88 then produces the following advantages: The magnetic system 88 may be made with smaller air gaps and, therefore, also with smaller volume of iron and despite that it may yield, for example, at twice nominal current, a sufciently high inductive component i2. The ohmic component i2 and the corresponding voltage drop in the main conductor 58 may be kept smaller. This is of importance for heating and for the short-circuit resistance of the main conductor 58. Shortened half-waves of current can be, moreover, realized with sufficiently longer time of a control advance tv. The circumstance that the control advance time tv is longer at moderate overcurrents than at full short-circuit currents appears to be a disadvantage. Because of the interrupting work at the control advance time tv at approximately 1.5 milliseconds at full short-circuit current amounts to approximately only 1% of that of asynchronously-operated breakers with the same interrupting capacity, and according to FIGS. 6-8 the interrupting Work hardly increases with smaller primary currents, despite longer release times, the aforementioned circumstance is practically unimportant.`

Instead of the interlock system with the latches, according to FIGS. 1 and 2, any other interlocks, such as curved levers, half-wave devices, and the like may be also considered for this application.

An approximately constant advance release time tv, in spite of saturation of the magnetic system 88, may be obtained also in that also the ohmic component i2 of the control current increases less than linearly with the increasing primary current il. Especially in circuit 4interrupters for large nominal currents, the ohmic resistance losses in the main conductor under some circumstances cannot be thermally controlled without additional auxiliary provisions. Because it is quite necessary for the Aadvance control to produce, besides the portion of the ilux produced by the inductive component i2', in the holding magnet 46, a second portion of the ux synchronized with current i1, smaller ohmic (resistance) losses in the main conductor, and a constant time advance release time tv can be obtained, for example, by a magnetic circuit connected magnetically with the holding magnet 46, but nevertheless energized from the main current i1, which magnetic circuit may also saturate at the larger-value main circuit currents, as shown in FIG. l0. Thus, the ohmic component of the control current i2 can be reduced, or entirely omitted.

An embodiment of the invention embodying this feature is shown in FIG. 10. Since the elements shown are the same as those illustrated in FIGURE 2, the same reference characters will be used. The holding magnet 46 is energized by the current owing through conductor 47, which produces a partial ilux across the armature 45 lagging the main current by degrees. Contrary to FIGURE 2, the conductor 47 surrounds the magnetic first circuit 88 which is energized by the main current i1 through the conductor 58. The second component of the ux across the armature 45 which is in synchronism with the main current i1, is produced by a second magnetic circuit which is energized by the main current (conductor 7). This magnetic circuit, as shown in FIG- URE 10, is magnetically conductively connected with the holding-magnet circuit 46 so that part of its flux goes through the armature 45. The two partial fluxes through the armature 45 coact in a similar manner as the inductive component i2 and the ohmic component i2 shown in FIGURE 9.

From the foregoing description it will be apparent that there is provided an improved synchronous control 4 and reclosing arrangement 67, 48 for a circuit interrupter, which is particularly suitable for a circuit interrupter pcf the gas-blast type in which arc extinction Iand reclosing energy is obtained from a source of compressed gas 79. It will be noted that the magnitude of the energy consumed during an interrupting operation is relatively low due to the fact that the contacts are separated only near a current zero during large magnitude currents of fault magnitude. Moreover, it will be apparent that the circuit interrupter 1 is of relatively small dimensions and composed of relatively few parts.

Although there has been illustrated and described a specic structure, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art, without departing from the spirit and scope of the invention.

We cl-aim as our invention:

1. In a synchronous-type circuit interrupter adapted to open an alternating-current main current circuit and having a pair of Vseparable contacts adapted to open a predetermined time prior to a current zero in said main circuit current being interrupted, the combination therewith -of :accelerating spring means biasing said pair of separable contacts to an open separated condition, latching means for latching the contacts in their closed currentcarrying condition, releasing means for releasing said latching means for eifecting release of the contacts to effect thereby opening of the interrupter, :said releasing means having a pair of release operators, one of which being a mechanical operator and the other of which being a magnetic holding rele-ase operator, means for generating a control current from the energy of the main circuit current which is a function of said main current and which is phase-shifted with respect to said main circuit current, and said magnetic holding release operator including a holding magnet energized by said phase-shifted control current.

2. In a `synchronous-type reclosing circuit interrupter having a pair of separable contacts adapted to open a predetermined time prior to a current zero in the main circuit current being interrupted, the combination therewith of accelerating spring means biasing said pair of separable contacts to an open separated condition, latching means for latching the contacts in their closed currentcarrying condition, releasing means for releasing said latching means for eifecting release of the contacts to effect thereby opening of the interrupter, said rele-asing means having a pair of release operators, one of which being a mechanical operator and the other of which being a magnetic holding release operator, means for generating a control current from the energy of the main circuit current which is a function of said main current and which is phase-shifted with respect to said main circuit current, said magnetic holding release operator including a holding magnet energized by said phase-shifted control current, a reclosing operator whereby the interrupter may i be reclosed upon unsuccessful synchronous interruption including means defining yan electromagnetic system having a magnetic circuit with at least one air gap, and a movable tripping control member movable within said air gap and carrying at least part of said phase-shifted control current to initiate a reclosing oper-ation.

3. In a synchronous-type compressed-gas circuit interrupter having a pair of separable contacts adapted to open a predetermined time prior to a current zero in the main current circuit being interrupted, and moreover having a valve-controlled blast of gas forced adjacent the separated contacts to effect the extinction of the established arc in a blast of gas, the combination therewith of accelerating spring means biasing said pair of separable contacts to an open separated condition, a pressure-operated piston operatively secured to one of the separated contacts to eiect the reclosing 4operation thereof, latching means for latching the contacts in their closed current-carrying condition, releasing means lfor releasing said latching means for effecting release of the contacts to eifect thereby opening of the interrupter, said releasing means having a pair of -release operators, one of which being a mechanical operator and the, other of which being a magnetic holding release operator, means for generating a control current from the energy of the main current which is a function of the main current and which is phase-shifted with respect to said main current, and said magnetic holding release operator including a holding magnet energized by said phase-shifted control current, a reclosing operator including a reclosing valve for supplying pressurized gas to said piston upon unsuccessful synchronous interruption including means defining an electromagnetic system having at least one air gap, and a movable tripping control member movable within said air gap and carrying at least part of said phase-shifted control current to initiate a reclosing operation, whereby said tripping member may eeot release of the latched-closed reclosing valve.

4. In combination, a synchronous-type alternating-current circuit interrupter having separable contacts and carrying current in a substantially axial path in an axial conductor, a control magnet system surrounding said axial conductor and having at least one air gap, an electrodynamic magnet system having an air gap and also surrounding said axial conductor, the two magnet systems being arranged in substantial axial alignment, mechanical latching means for latching the separable contacts in the closed position, spring accelerating means for biasing the contacts to an open position, releasing means for said latching means including an initial rst operator and a second timing operator, said latching means being released only upon the first and second operators being in their actuated condition, means for actuating the first operator at any time on the current wave, a holding magnet associated with said second operator, means energizing said holding magnet including a control circuit threading said control magnet system and having a movable control conductor, and reclosing means for the separable contacts including said movable control conductor movable within the air gap of the electrodynamic magnet system.

5. In a synchronous-type circuit interrupter adapted to open an alternating-current main current circuit and having a pair of separable contacts adapted to open a predetermined time prior to a current zero in said main circuit current being interrupted, the combination therewith of accelerating spring means biasing said pair of separable contacts to an open separated condition, latching means for latching the contacts in their closed current-carrying condition, releasing means for releasing said latching means for effecting release of the contacts to elfect thereby opening of the interrupter, said releasing means having a pair of release operators, one of which being a mechanical operator and the other of which being a magnetic holding release operator, a magnetic control circuit encircling the main current path of the interrupter, means for generating a control current from the energy of the main current circuit which is a function of said main current and which is phase-shifted with respect to said main current circuit, said control current being produced by two voltages, one of which is an inductive voltage and is approximately ninety degrees out of phase with the main current and is proportional to the rate of change of flux produced in said magnetic circuit by said main current, and the other voltage component being ohmic and in phase with said main current, whereby the circuit is designed so that the ohmic voltage acts against the inductive voltage when the main current is decreasing, and said magnetic holding and release operator including a holding magnet energized by said phase shifted control current.

6. The combination of claim 5, wherein a main conductor carries at least a portion of the main current circuit, and the ohmic voltage is obtained as a voltage drop through a part of said conductor.

7. In a synchronous-type circuit interrupter adapted to open an alternating-current main current circuit and having a pair of separable contacts adapted to open a predetermined time prior to a current zero in said main circuit current being interrupted, the combination therewith of a conductor and surrounding magnetic structure constituting in effect a bar-type current transformer, accelerating spring means biasing said pair of separable contacts to an open separated condition, latching means for latching the contacts in their closed current carrying condition, releasing means for releasing said latching means for effecting release of the contacts to effect thereby opening of the interrupter, said releasing means having a pair of release operators, one of which being a vmechanical operator and the other of which being a magnetic holding release operator, means including a secondary circuit through said bar-type current transformer for generating a control current from the energy of the main current circuit and which is phase-shifted with respect to said main current circuit, said control current produced by two voltages, one of which is an inductive voltage and the other of which is an ohmic voltageacting between spaced points on the bar-type single conductor of the bar-type current transformer, and said magnetic holding releasey operator including a holding magnet energized by said phase-shifted control current.

8. The combination according to claim 7, wherein the part of the main conductor extending between said spaced points consists of a material which has a resistance of at least 3 10*1 ohms.

9. The combination according to claim 1, wherein the predetermined time is at the most two milliseconds before current zero.

j 10. The combination according to claim 2, wherein the magnetic circuit of the electrodynamic system at approximately twice the normal current has an air gap induction of at least fifteen thousand gauss.

J 11. A synchronous-type circuit interrupter including a pair of separable contacts for interrupting a main alternating current circuit, means biasing said pair of separable contacts to the open-circuit position, latching means for maintaining said contacts in engaged position against the bias exerted by said biasing means, releasing means incl-uding a holding magnet, means for generating magnetic flux within said holding magnet including two current components, one current component being substantially in phase with the main current being interrupted, and the other current component being substantially 90 out of phase with said main current.

j 12. A synchronous-type circuit interrupter including a pair of separable contacts for interrupting a main current, a magnetic control circuit encompassing said main current and having a closed secondary winding including a main conductor portion extending through the magnetic circuit, means biasing said pair of separable contacts to Vthe open-circuit position, latching means for maintaining said contacts in engaged position against the bias exerted by said biasing means, releasing means including a holding magnet, means for generating magnetic flux within said holding magnet including said closed secondary winding whereby there are two current components, one cur- `rent component being substantially in phase with the main current being interrupted, and the other current component being substantially 90 out of phase with said lmain current.

13. A synchronous-type circuit interrupter including a pair of separable contacts for interrupting a main alternating current circuit, means biasing said pair of separable contacts to the open-circuit position, latching means for maintaining said contacts in engaged position against the bias exerted by said biasing means, releasing means including a holding magnet, means for generating magnetic 40 ux within the said holding magnet having one ux component which is out of phase with respect to the main current, and another iiux component which is in phase with respect to the main current.

14. A synchronous-type circuit interrupter including a pair of separable contacts for interrupting a main current, means biasing said pair of separable contacts to the open-circuit position, latching means for maintaining said contacts in engaged position against the bias exerted by said biasing means, releasing means including a holding magnet, means for generating magnetic ux within the said holding magnet including an auxiliary holding magnetic circuit surrounding at least a portion of the main current and is in flux-transmitting relationship with said holding magnet, said flux generating means also including a holding-magnet winding having an inductive component which is approximately in phase with the time change of iux in a magnet system energized by the main current.

15. A synchronous-type alternating-current circuit interrupter including a pair of separable contacts for interrupting a main current, means biasing said pair of separable contacts to the open-circuit position, a rst magnetic circuit energized by at least a portion of said main current, a second magnetic circuit energized by at least a portion of said main current, latching means for maintaining said contacts in engaged position against the bias exerted by said biasing means, releasing means Afor said latching means including a holding magnet, means electrically coupling said holding magnet with said rst magnetic circ-uit, and means magnetically coupling said second magnetic circuit with said holding magnet so that the combined fluxes in said holding magnet will drop to substantially zero a predetermined time prior to a normal current zero.

References Cited by the Examiner UNITED STATES PATENTS 1,292,651 1/19 Rippl 200-98 X 1,794,682 3/31 Greenwood 200-148 2,196,868 4/40 Kramer 200-91 X 2,499,394 3 50 Kesselring. 2,672,541 3/54 Paul 20G- 148 3,114,815 12/63 Easley et al. 200-148 FOREIGN PATENTS 422,775 1/35 Great Britain. 718,985 11/54 Great Britain.

KATHLEEN H. CLAFFY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

1. IN A SYNCHRONOUS-TYPE CIRCUIT INTERRUPTER ADAPTED TO OPEN AN ALTERNATING-CURRENT MAINT CURRENT CIRCUIT AND HAVING A PAIR OF SEPARABLE CONTACTS ADAPTED TO OPEN A PREDETERMINED TIME PRIOR TO A CURRENT ZERO IN SAID MAIN CIRCUIT CURRENT BEING INTERRUPTED, THE COMBINATION THEREWITH OF ACCELERATING SPRING MEANS BIASING SAID PAIR OF SEPARABLE CONTACT TO AN OPEN SEPARTED CONDITION, LATCHING MEANS FOR LATACHING THE CONTACT IN THEIR CLOSED CURRENTCARRYING CONDITION, RELEASING MEANS FOR RELEASING SAID LATCHING MEANS FOR EFFECTING RELEASE OF THE CONTACTS TO EFFECT THEREBY OPENING OF THE INTERRUPTER, SAID RELEASING MENS HAVING A PAIR OF RELEASE OPERATORS, ONE OF WHICH BEING A MECHANICAL OPERATOR AND THE OTHER OF WHICH BEING A MAGNETIC HOLDING RELEASE OPERATOR, MEANS FOR GENERATING A CONTROL CURRENT FROM THE ENERGY OF THE MAIN CIRCUIT CURRENT WHICH IS A FUNCTION OF SAID MAIN CURRENT AND WHICH IS PHASE-SHAFTED WITH RESPECT TO SAID MAIN CIRCUIT CURRENT, AND SAID MAGNETIC HOLDING RELEASE OPERATOR INCLUDING A HOLDING MAGNET ENERGIZED BY SAID PHASE-SHIFTED CONTROL CURRENT. 